1. Field of the Invention
The present invention relates to an artificial-photosynthesis array that has a plurality of artificial-photosynthesis modules that receive light to decompose water and manufacture hydrogen and oxygen, and particularly, to an artificial-photosynthesis array that can keep an ion concentration or pH value in water constant.
2. Description of the Related Art
In the related art, as one form of using solar light energy that is a renewable energy, there are suggested hydrogen manufacturing apparatuses that utilize electrons and positive holes obtained by photoelectric conversion for a decomposition reaction of water, using a photoelectric conversion material used for solar batteries, and thereby manufacture hydrogen used for fuel cells or the like (for example, refer to JP2012-177160A and JP2012-41623A).
In the hydrogen manufacturing apparatus disclosed in JP2012-177160A, a photoelectric conversion part or a solar battery in which two or more pn junctions that generate an electromotive force if solar light enters are connected in series is provided, an electrolytic solution chamber is provided on a lower side of the photoelectric conversion part or the solar battery opposite to a light-receiving surface that receives solar light on an upper side of the photoelectric conversion part, and the inside of an electrolytic chamber is divided by the ion-conducting partition wall or a diaphragm. In JP2012-177160A, water is electrolyzed within the electrolytic solution chamber by the electrical energy generated in the photoelectric conversion part or the solar battery by the reception of solar light, and thereby hydrogen gas and oxygen gas are generated.
In the hydrogen manufacturing apparatus disclosed in JP2012-177160A, the orientation of the light-receiving surface with respect to solar light can be adjusted. Thus, the amount of incident light to be photoelectrically converted can be increased, and hydrogen generation efficiency is not lowered.
Additionally, a water electrolysis apparatus disclosed in JP2012-41623A has a light-receiving surface and a rear surface thereof, and includes a photoelectric conversion part in which a potential difference is caused between the light-receiving surface and the rear surface by receiving light, a first electrode for electrolysis that is provided on the rear surface side of the photoelectric conversion part and is electrically connected to the rear surface of the photoelectric conversion part, a second electrode for electrolysis that is provided on the rear surface side of the photoelectric conversion part and is electrically connected to the light-receiving surface of the photoelectric conversion part, and a flow path provided so that water flows therethrough. The first electrode for electrolysis and the second electrode for electrolysis are provided so as to be immersible in the water within the flow path, and are provided so as to electrolyze water with an electromotive force generated by the photoelectric conversion part receiving light and thereby generate hydrogen gas and oxygen gas, respectively. Either the first electrode for electrolysis or the second electrode for electrolysis is a hydrogen generating part, and the other is an oxygen generating part.
The flow path is constituted of a first flow path in which the first electrode for electrolysis is formed within the flow path, a second flow path in which the second electrode for electrolysis is formed within the flow path, and a communication flow path, and a partition wall is provided so as to partition off the first flow path from the second flow path. There are a plurality of first flow paths and a plurality of second flow paths, and these flow paths are provided alternately and parallel to each other, and a first flow path and a second flow path adjacent to each other are able to communicate with each other via the communication flow path.